Implement load transfer

ABSTRACT

An apparatus is disclosed having hydraulic means for exerting a variable downward force on the tongue of a tractor drawn implement to optimize the tractive pull of the tractor. The apparatus is carried by the implement and includes a linear device connected to sense the drawing force exerted upon the implement and a second linear device connected between the implement and its tongue to exert a downward force upon the tongue that is a function of the drawing force sensed by the first device.

United States Patent Reinhardt 51 June 20, 1972 [54] IMPLEMENT LOADTRANSFER [72] Inventor: Robert L. Reinhardt, Lubbock, Tex.

[73] Assignee: Clark Equipment Company [22] Filed: July 2, 1970 [2]]Appl No.: 52,036

[52] [1.8. CI ..l72/7, 172/781, 280/405, 280/446 [51] Int. Cl ..B62d53/00 [58] Field of Search ..280/405, 446, 406; 172/781, 172/7 [56]References Cited UNITED STATES PATENTS 3,063,740 11/1962 Hancock..280/405 R 3,073,622 1/1963 Merritt ..280/405B FOREIGN PATENTS ORAPPLICATIONS 487,895 6/1938 Great Britain ..280/405 R PrimaryExaminer-Leo Friaglia Attorney-Kenneth C. Witt, John C. Wiessler, RobertH. Johnson and Reginald .l. Falkowski [57] ABSTRACT An apparatus isdisclosed having hydraulic means for exerting a variable downward forceon the tongue of a tractor drawn implement to optimize the tractive pullof the tractor. The apparatus is carried by the implement and includes alinear device connected to sense the drawing force exerted upon theimplement and a second linear device connected between the implement andits tongue to exert a downward force upon the tongue that is a functionof thedrawing force sensed by the first device.

4 Claims, 4 Drawing figures PATENTEDaunzo 1972 SHEET 10F 2 INVENTORROBERT L. REINHARDT ATTORNEY PATENTEDwuzo I972 SHEET 2 [IF 2 mm y.

JNVENTOR ROBERT L. REINHARDT ATTORNEY IMPLEMENT LOAD TRANSFER BACKGROUNDOF THE INVENTION When a four wheeled tractor is used to pull animplement by means of a tongue or drawbar, the drawing force that may beexerted is dependent upon both the capability of the tractor power plantand upon the traction or effectiveness with which the tractor drivingwheels engage the ground. The tractive effort of the driving wheels maybe substantially increased by increasing the downward force exerted uponthem and, because the mere addition of weight to the tractor oftenentails added expense in both cost and performance, it is known foreither the tractor or the implement to comprise an apparatus thattransfers a portion of the implement's weight to the driving wheels toaugment their tractive effort. Weight transfer ap paratuses. carried bythe implement and forming a part of the implement's tongue or drawbarare usually preferable over those carried by the tractor because they donot require the mating of a particular implement with a speciallyequipped tractor, and also because they may be designed to fulfill anyunique requirements of the implement. Some such weight transferapparatuses are designed to transfer a constant amount of the implementsweight to the tractor driving wheels regardless of the draft load ortractor implement orientation, while other apparatuses are designed totransfer only sufficient weight to maintain the drawing force constant.Advanced weight transfer apparatuses are. designed to transfer avariable amount of the implements weight to the tractor driving wheelsdepending as a function on the variable drawing force. In this mannerthe tractor's capabilities are most efficiently utilized throughout itsdrawing operation because it is not overburdened when its work is lightor insufficiently loaded when its work is heavy.

SUMMARY OF THE INVENTION In carrying out my invention in one preferredfonn thereof, I provide an apparatus for exerting a downward force onthe tongue of a drawn implement that varies as a selected function ofthe drawing force exerted upon the implement. The apparatus is carriedby the implement and comprises a linear fluid device connected to sensethe drawing force and another linear fluid device connected between theimplement and its tongue to exert the downward force in response to thedrawing force sensed.

' BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic view of atractor operatively connected to a draft implement and embodying thisinvention,

FIG. 2 is an enlarged perspective view of a portion of FIG. 1 showingthe implement tongue in more detail,

FIG. 3 is a sectional view taken along the axis of the tongue of FIG. 2to illustrate certain components contained within the tongue, and

FIG. 4 is a schematic diagram of the hydraulic circuit disclosed in thisembodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT gooseneck Referring to FIGS. 1and 2, the numeral designates a tractor and the numeral 12 designates animplement such as an earth handling device or elevating scraper.lrnplement 12 has a tongue 14 of hollow construction having an open end16 and a yoke end 18 comprising spaced arms 20 and 22 secured to an axle24 which carries a pair of wheels 26. The tongue is rigidly mounted toaxle 24 by arms 20 and 22 by suitable means, such as welding indicatedat 28. The implement also includes a gooseneck 30 of tubularconstruction for attachment to a fifth wheel assembly indicatedgenerally at 32.

Mounted for fore and aft rocking on axle 24 at substantially the centerthereof is a post or block member 34 having forwardly and rearwardlyextending flanges 36 and 38, and a semicircular portion in its lower endas indicated at 40 which bears upon the upper side of the axle. A plateor hearing member 42 having a semicircular portion 44 and flanges 46 and48 adapted to mate with flanges 36 and 38 is provided for engaging theunderside of the axle. Flanges 36 and 38 and 46 and 48 are provided withaligned openings for receiving bolts 50 therethrough to detachable androtatably mount block 34 on axle 24, so that the two semicircularportions 40 and 44 provide a bearing for the block on the axle. Axle24is provided with a collar 52 on one side of block 34 that operates inconjunction with a similar second collar (not shown) on the other sideof block 34 to prevent lateral movement of the block on the axle.

Referring to FIGS. 2 and 3, gooseneck 30 includes forwardly extendingspaced horizontal plates 54 and 56 having aligned openings 58 and 60therethrough for receiving fifth wheel assembly 32 and also havingvertical sides 62 and 64. Fifth wheel assembly 32 includes a tubularmember 66 that extends vertically through openings 581 and 60 and hasits lower end welded or otherwise suitably secured to the top plate 68of a yoke member 70 which has depending spaced arms 72 and 74 providedwith aligned openings 76 and 78. Block 34 has an opening 80longitudinally of the implement and a bolt 82 engages in said openingand the openings 76 and 78 to pivotally mount gooseneck 30 of theimplement to axle 24 for transverse or lateral pivotable movement of theaxle relative to the implement when wheels 26 are on uneven ground.

A wear washer 84 is provided for surrounding the lower end of thetubular member 66 and engages the lower surface of plate 56. A sleeve 86surrounds tubular member 66 having its lower end engaging wear washer 84and extending loosely through opening 60 and its upper end connected toplate 54 of the gooseneck 30. The cap 88 is secured to tubular member 66by stud bolts 90 that engage in the threaded sockets 92 disposed inmember 66 to retain gooseneck 30 on fifth wheel assembly 32.

Rigidly secured to member 70 by welding or other suitable means is apair of spaced brackets 94 and 96 having aligned openings for receivinga pin 98 therethrough. Connected to pin 98 is a universal type jointindicated at 100 having a single acting piston and cylinder type linearfluid device 102 connected thereto to permit device 102. to swivel orturn at any angle defined limits while transferring forces with member70. Device 102 is of thetype commonly used in the hydraulic art andcomprises a cylinder 104, a piston 106 slidably disposed in the cylinderthat defines with cylinder 104' a head end fluid chamber 108, and apiston rod 110 connected to the piston and extending outwardly throughone end of the cylinder. Piston rod 110 is pivotally connected to theupper surface 112 of tongue 14 by means of a pin 114 extending throughrod 110 and also through aligned openings 116 in a pair of spacedtriangular shaped brackets l 18 and 120 welded to tongue 14. Referringspecifically to FIG. 3, a linear fluid device 122 that is adapted tosense the drawing force of tractor 10 and is similar to device 102 isdisposed within tongue 14 and comprises a cylinder 124, a piston 126slidably disposed in the cylinder that defines with cylinder 124 a rodend fluid chamber 128, and a piston rod 130 connected to the piston andextending outwardly through one end of cylinder 124. Cylinder 124 ispivotally connected to yoke 18 by means of a pin 132 through a bracket134 connected to yolte 18 and a bracket 136 connected to cylinder 124.Piston rod 130 is adapted to receive a portion of of the drawing forceand is pivotally connected by a pin 138 to the end 140 of a connectingbar or rod 142. Connecting bar 1142 has its other end 144 extendingthrough the opening 16 in the outerend of the tongue and has abifurcated or clevis end 146 for attachment to a drawbar 148 of thetractor by a pin 150 for a swinging pivotal movement of the tongue withrespect to the drawbar when turning the tractor. The opening 16 in theend of tongue 14 is provided with a bushing 152 through which connectingbar 142 is slidably disposed to prevent excessive transverse movementbetween the bar and the tongue. Connected near the end 140 of bar 142 isa sleeve 154 of a selected length that has a flange 156 thereon forretaining one end of a spring 158. The other end of spring 158 abuts ashoulder 160 of bushing 152 so that, during normal operation, thevariable drawing force of tractor is transmitted to tongue 14 partiallythrough spring 158 and partially through device 122. In the event thatthe tractor drawing force becomes excessive, sleeve 154 is adapted toabut shoulder 160 for the direct transmission of forces from tractor 10to tongue 14, thereby limiting the operation of spring 158 to itselastic range and the operation of piston 126 within cylinder 124.

Referring now to FIG. 4, the hydraulic circuit comprising fluid devices102 and 122 is shown schematically. The rod end chamber 162 of device102 and the head end chamber 164 of device 122 are provided with abreather 166 of a common type that is adapted to maintain the chambersat ambient pressures while protecting the chambers from dirt and othercontaminants. The head end fluid chamber 108 of device 102 and the rodend fluid chamber 128 of device 122 are interconnected for fluidcommunication by a flexible hydraulic hose 168 and it will now berecognized that devices 122 and 102 bear a master-slave relationship toeach other. Hose 168 provides a source of makeup fluid from a reservoir170 that is hydraulically connected to hose 168 through a valve system172 and a secondary hydraulic hose 174. Valve system 172 comprises threevalves in parallel flow relationship; a manual valve 176 permitting theeasy raising and lowering of tongue 14 during tractor hookup and theselection of a downward force for normal operation, and a one way checkvalve 178 and relief valve 180 that in concert permit controlled downpressure and compensate for differential volumes between chamber 108 andchamber 128 during operation. The relative volumes of chambers 108 and128 and relative areas of pistons 106 and 126 may be selected to providea desired functional relationship between the travel of rods 110 and 130and also between the drawing force upon connecting bar 142 and thedownward force upon tongue 14.

In operation, the drawing force of tractor 10 urges connecting bar 142to translate forward slightly within tongue 14. The forward movement ofbar 142 is increasingly resisted by spring 158 and device 122 untilsuflicient force is transmitted to implement 12 that it begins to track.if the progress of implement 12 is impeded as it moves across unevenground the drawing force exerted upon bar 142 will be increased and thebar will be drawn slightly forward relative to tongue 14 by tractor 10.As bar 142 moves forward, device 122 senses the increased drawing forceas reflected in the reduced volume of fluid chamber 128 and increasedpressure of the fluid contained therein so that hydraulic fluid istransferred through hose 168 to pressurize fluid chamber 108, therebyextending device 102 and exerting a downward force upon tongue 14 andbar 142. The downward force upon bar 142 is transferred through drawbar148 to the traction wheels 182 of tractor 10 for a greater tractiveeffort in overcoming the impedance of implement 12. When the drawingforce exerted upon bar 142 returns to its operating level, spring 158urges bar 142 and piston 126 toward their selected operating positionand the downward force upon wheels 182 reduces to a level selected formost efficient operation. I

While I have described and illustrated herein a preferred embodiment ofmy invention, incorporated in one type of implement, it will be apparentto those skilled in the art that my invention may be incorporated in avariety of implements and that other embodiments and modifications ofthe invention may be made. It should be understood therefore, that Iintend to cover by the appended claims all modifications and variationswhich fall within the true spirit and scope of my invention.

I claim:

1. An apparatus for exerting a downward force on the tongue of a drawnimplement comprising a first linear fluid device connected to theimplement to sense the'drawing force exerted upon the implement and asecond linear fluid device connected between the implement and thetongue, said first device comprising relatively reciprocal first pistonand cylinder elements, one said first element connected to receive aportion of said drawing force and the other said first element connectedto the implement, said first piston defining within said first cylinderfirst and second fluid chambers, the fluid pressure in said firstchamber transferring the portion of said drawing force received by saidone first element to said other first element, and wherein said seconddevice comprises relative reciprocal second piston and cylinderelements, one said second element connected to the implement and theother said second element connected to the tongue, said second pistondefining within said second cylinder third and fourth fluid chambers,said first chamber connected for fluid communication with said thirdchamber so that the fluid pressure in said third chamber is maintainedsubstantially equivalent to the prwsure in said first chamber, thepressure in said second chamber and said fourth chamber being maintainedsubstantially constant and wherein the apparatus also comprises a valvesystem connected for fluid communication with said first and thirdchambers, said valve system comprising means for selecting the volume ofsaid first and third chambers when a selected drawing force is receivedby said first device and for limiting the fluid pressure in said firstand third chambers to a selected maximum, and a spring connected to saidone first element and to the implement, said spring transfening aportion of said drawing force to the implement and also urging said onefirst element toward a selected position and a sleeve having a selectedlength connected to said one first element, said sleeve providing meansfor limiting the travel of said one first element relative to said otherfirst element and also for limiting the compression of said spring.

2. An earth moving apparatus having a cutting element engageable withthe ground adapted to be drawn by a tractor comprising a tonguepivotally connected thereto in front of said element, a portion of saidtongue trailingly engageable with said tractor and being of hollowconstruction and containing therein a first linear fluid device having afirst piston slidably disposed within a first cylinder, one beingconnected to said tongue and said other connected to receive a portionof the drawing force exerted upon said portion of the tongue, said firstpiston defining with said first cylinder, a first fluid chamber, asecond linear fiuid device having a second piston slidably disposedwithin a second cylinder, one connected to the apparatus above saidportion of the tongue and the other connected to said tongue portion,said second piston defining with said second cylinder a second fluidchamber, said second fluid chamber connected for fluid communicationwith said first fluid chamber, a connecting bar, one end of saidconnecting bar being connected to said first fluid device and the otherend of said connecting bar extending slidably through a bushing in theouter end of said tongue portion, said bushing fitting loosely aroundsaid bar to prevent excesive transverse movement of said bar within saidtongue portion, a sleeve of selected length connected to said one end ofsaid connecting bar and having a flange thereon, said sleeve abuttingsaid bushing when said connecting bar translates forward a predeterminedamount relative to said tongue portion, a spring connected to saidflange and to said tongue portion, said spring transferring a portion ofsaid drawing force to said tongue portion and also urging said firstfluid device toward a selected position, and, a valve system for theselected fluid connection of said first and second fluid chambers with afluid reservoir, said valve system comprising a manual valve forselecting the volume of said first and second chambers, a one way checkvalve allowing flow only from said reservoir to said chambers, and apressure relief valve allowing flow from said chambers to said reservoironly when the fluid pressure in said chambers exceeds a selected value.

3. In an earth moving apparatus having a tongue connected to a cuttingelement engageable with the ground adapted to be drawn by a tractor, theimprovement comprising a first relatively reciprocal piston and cylinderunit housed within said tongue, is drawbar connected to one element ofsaid unit reciprocally mounted coaxially of said tongue and said otherelement being secured within said tongue to permit relative axialmovement of said piston and cylinder elements upon ap plication ofdrawing force to said drawbar, a supporting axle for said apparatusextending transversely to said tongue and carrying ground engagingwheels at each end thereof, means fixedly connecting said axle andtongue, a post member rockably mounted centrally of said axle andextending upwardly therefrom, means on said post member pivotallysupporting said apparatus, a second relatively reciprocal piston andcylinder unit, one element of said second unit being connected to saidtongue and the other being connected to said rockable post memberadjacent its upper end, hydraulic fluid conduit means connecting thefirst and second piston and cylinder units wherein the second is inslave relationship to the first such that the application ofa drawingforce tends to cause a proportionate extension of the drawbar and firstunit producing a corresponding extension of the second unit therebytending to rotate said post member and tongue oppositely about saidaxle.

4. The improvement according to claim 3 wherein said means connectingthe axle and tongue comprises a yoke secured to the tongue havinglaterally spaced arms secured to the axle on opposite sides of thecenterline of the apparatus and said post member being rockably mountedintermediate said arms.

i l B i l

1. An apparatus for exerting a downward force on the tongue of a drawnimplement comprising a first linear fluid device connected to theimplement to sense the drawing force exerted upon the implement and asecond linear fluid device connected between the implement and thetongue, said first device comprising relatively reciprocal first pistonand cylinder elements, one said first element connected to receive aportion of said drawing force and the other said first element connectedto the implement, said first piston defining within said first cylinderfirst and second fluid chambers, the fluid pressure in said firstchamber transferring the portion of said drawing force received by saidone first element to said other first element, and wherein said seconddevice comprises relative reciprocal second piston and cylinderelements, one said second element connected to the implement and theother said second element connected to the tongue, said second pistondefining within said second cylinder third and fourth fluid chambers,said first chamber connected for fluid communication with said thirdchamber so that the fluid pressure in said third chamber is maintainedsubstantially equivalent to the pressure in said first chamber, thepressure in said second chamber and said fourth chamber being maintainedsubstantially constant and wherein the apparatus also comprises a valvesystem connected for fluid communication with said first and thirdchambers, said valve system comprising means for selecting the volume ofsaid first and third chambers when a selected drawing force is receivedby said first device and for limiting the fluid pressure in said firstand third chambers to a selected maximum, and a spring connected to saidone first element and to the implement, said spring transferring aportion of said drawing force to the implement and also urging said onefirst element toward a selected position and a sleeve having a selectedlength connected to said one first element, said sleeve providing meansfor limiting the travel of said one first element relative to said otherfirst element and also for limiting the compression of said spring. 2.An earth moving apparatus having a cutting element engageable with theground adapted to be drawn by a tractor comprising a tongue pivotallyconnected thereto in front of said element, a portion of said tonguetrailingly engageable with said tractor and being of hollow constructionand containing therein a first linear fluid device having a first pistonslidably disposed within a first cylinder, one being connected to saidtongue and said other connected to receive a portion of the drawingforce exerted upon said portion of the tongue, said first pistondefining with said first cylinder, a first fluid chamber, a secondlinear fluid device having a second piston slidably disposed within asecond cylinder, one connected to the apparatus above said portion ofthe tongue and the other connected to said tongue portion, said secondpiston defining with said second cylinder a second fluid chamber, saidsecond fluid chamber connected for fluid communication with said firstfluid chamber, a connecting bar, one end of said connecting bar beingconnected to said first fluid device and the other end of saidconnecting bar extending slidably through a bushing in the outer end ofsaid tongue portion, said bushing fitting loosely around said bar toprevent excessive transverse movement of said bar within said tongueportion, a sleeve of selected length connected to said one end of saidconnecting bar and having a flange thereon, said sleeve abutting saidbushing when said connecting bar translates forward a predeterminedamount relative to said tongue portion, a spring connected to saidflange and to said tongue portion, said spring transferring a portion ofsaid drawing force to said tongue portion and also urging said firstfluid device toward a selected position, and, a valve system for theselected fluid connection of said first and second fluid chambers with afluid reservoir, said valve system comprising a manual valve forselecting the volume of said first and second chambers, a one way checkvalve allowing flow only from said reservoir to said chambers, and apressure relief valve allowing flow from said chambers to said reservoironly when the fluid pressure in said chambers exceeds a selected value.3. In an earth moving apparatus having a tongue connected to a cuttingelement engageable with the ground adapted to be drawn by a tractor, theimprovement comprising a first relatively reciprocal piston and cylinderunit housed within said tongue, a drawbar connected to one element ofsaid unit reciprocally mounted coaxially of said tongue and said otherelement being secured within said tongue to permit relative axialmovement of said piston and cylinder elements upon application ofdrawing force to said drawbar, a supporting axle for said apparatusextending transversely to said tongue and carrying ground engagingwheels at each end thereof, means fixedly connecting said axle andtongue, a post member rockably mounted centrally of said axle andextending upwardly therefrom, means on said post member pivotallysupporting said apparatus, a second relatively reciprocal piston andcylinder unit, one element of said second unit being connected to saidtongue and the other being connected to said rockable post memberadjacent its upper end, hydraulic fluid conduit means connecting thefirst and second piston and cylinder units wherein the second is inslave relationship to the first such that the application of a drawingforce tends to cause a proportionate extension of the drawbar and firstunit producing a corresponding extension of the second unit therebytending to rotate said post member and tongue oppositely about saidaxle.
 4. The improvement according to claim 3 wherein said meansconnecting the axle and tongue comprises a yoke secured to the tonguehaving laterally spaced arms secured to the axle on opposite sides ofthe centerline of the apparatus and said post member being rockablymounted intermediate said arms.